1. Field of the Invention
The present invention relates to a clamp apparatus which converts the rectilinear motion of a cylinder into the rotary motion by means of a toggle mechanism to clamp a workpiece with an arm. In particular, the present invention relates to a clamp apparatus which is provided with a release means for releasing the arm from clamped state to unclamped state wherein the release means is protected by an openable/closable cover member.
2. Description of the Related Art
In general, a release means of a closed type power clamp apparatus has a projection for releasing a toggle section from a housing, and the projection protrudes from the housing, as disclosed in U.S. Pat. No. 5,575,462. When such a power clamp apparatus is used in arc welding, the projection is covered with a cover so that no spatter is adhered to the projection. When the toggle section is released, the cover should be detached to make the toggle section unclamped, and then the cover should be attached again. That is, the operation to detach the cover and attach the cover is required for releasing the toggle section. Therefore, the operation process is complicated, and a considerably long period of time is required. As a whole, the production efficiency is not improved so much.